CA1168064A - Device for positioning a test strip for optical- medical measurements - Google Patents
Device for positioning a test strip for optical- medical measurementsInfo
- Publication number
- CA1168064A CA1168064A CA000372953A CA372953A CA1168064A CA 1168064 A CA1168064 A CA 1168064A CA 000372953 A CA000372953 A CA 000372953A CA 372953 A CA372953 A CA 372953A CA 1168064 A CA1168064 A CA 1168064A
- Authority
- CA
- Canada
- Prior art keywords
- test strip
- pressing
- spring
- strip
- test
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/84—Systems specially adapted for particular applications
- G01N21/8483—Investigating reagent band
Abstract
ABSTRACT OF THE DISCLOSURE
The present invention provides a device and method for positioning and firmly holding a test strip for optical-medical measurements, said device comprising a housing with a reception opening, on the inner end of which there is a stop for the test strip, and a window which is positioned opposite the test zone of a test strip inserted into the reception opening and lying against the stop, wherein said device also comprises a pressing mechanism acting substantially at right-angles on the rear side of the test strip, which pressing mechanism, when inserting a test strip, is in a resting position remote from the test strip and, when the test strip is lying against the stop, is adapted to move into a pressing position in which it presses the test strip against the window, the pressing force of said pressing mechanism being sub-stantially uniform in the positions corresponding to various thicknesses of the test strips.
The present invention provides a device and method for positioning and firmly holding a test strip for optical-medical measurements, said device comprising a housing with a reception opening, on the inner end of which there is a stop for the test strip, and a window which is positioned opposite the test zone of a test strip inserted into the reception opening and lying against the stop, wherein said device also comprises a pressing mechanism acting substantially at right-angles on the rear side of the test strip, which pressing mechanism, when inserting a test strip, is in a resting position remote from the test strip and, when the test strip is lying against the stop, is adapted to move into a pressing position in which it presses the test strip against the window, the pressing force of said pressing mechanism being sub-stantially uniform in the positions corresponding to various thicknesses of the test strips.
Description
1680~4 The present invention is concerned with a device and method for positioning and firmly holding a test strip for optical-medical measurements.
Moxe particularly the device comprises a housing with a reception opening, on the inner end of which there is a stop for the test strip, and a window which is positioned opposite the test zone of a test strip inserted into the reception opening and lying against the stop.
The precise positioning of a medical test strip in an appropriate evaluation device, usually a remission photometer, is of decisive importance for the exactitude of the evaluation of the test strip. On the one hand, it is, of course, important that the test strip lies, in the longitudinal direction, correctly below the window of the optical measuring device in order that only the appropriate test zone lies in the measurement area and not perhaps a part of the carrier material, which would falsify the measurement result. On the other hand, it is extremely important that the distance between the optical measuring device and the surface of the test zone can be reproduced very precisely because, depending upon the construction of the optical system, the measured intensity enters into the result with the second to fourth power of the distance between the measurement field and the photoreceiver. In the case of a typical distance of 8 mm., a variation of the distance of only 0.1 mm. gives an error which is from 2.5 to 5%. Especial difficulties arise from the fact that, if possible, test strips of different manufacture and for ..~g different medical parameters are to be measured with one apparatus. The thickness of these test strips can differ considerably in the region of the test zone.
In the case of known apparatus, the test strips are introduced into a device provided therefor and firmly held in the measurement position by means of a leaf spring. In these devices, positioning is un-satisfactory not only in the longitudinal direction of the test strip but also with regard to the distance from the optical measuxement system. It can happen relatively easily that when the test strip is inserted, it does not lie completely against the stop because the leaf spring has already exerted a considerable resist-ance to the insertion. On the other hand, it can also quite easily happen that the test strip, after insertion, is again pulled out of the apparatus to a small extent, especially when the hands of the person operating the device are moist, which can frequently occur in the laboratory, and consequently stick somewhat to the test strip.
Furthermore, as has been recognized by the present invention, positioning at right-angles to the surface of the test strip can also be insufficiently exact when test strips of varying thickness are to be measur~d. Thus, the tension of the leaf spring is to a considerable extent, dependent upon the thickness of the test strip. The distance between the test zone and the optical measurement system also changes correspondingly to an extent which is unacceptable when a high degree of .
1 1~8~4 exactitude of the measurement is required.
Oftentimes the window in the reception opening has to be an open frame (e.g. to allow air to be in contact with the test piece) and in these cases the unsatisfactory results with known devices can easily be explained by the fact that different test zones are pressed into this frame to a different extent.
However, in the present invention it has been found, that even in apparatus with a firmly positioned closed window, for~ example of glass, the measuring results depend in most cases heavily on the strength of the force by which the test zone is pressed against the window.
Therefore, it is an object of the present invention so to improve the position of the test strips for optical-medical measurements that a very accurate measurement result is achieved.
.
.'5 680~
In one aspect of the invention there is provided a device for positioning and firmly holding a test strip for optical-medical measurements' the device includes a housing which has a passage for receiving a test strip having a test zone for optical examination, a stop in the housing limits insertion of the strip in the passage; a window is provided which is adapted to be in opposed ; relationship with the test zonej when the inner end of the strip is against the stop' a pressing means is moveable from a rest position remote from the strip to a holding `~ position in which the test zone is urged against the window, when the inner end of the strip is against the stop. In this way the test zone of the strip is positioned and firmly held against the window~
In a particularly advantageous embodiment the pressing means transmits a substantially uniform pressing force to the strip, independently of the thickness of the strip.
Thus, in particular the invention provides a device for positioning and firmly holding a test strip for optical-medical measurements, said device comprising a housing with a reception opening, on the inner end of which there : is a stop for the test strip, and a window which is positloned opposite the test zone of a test strip inserted 0 ~ 4 into the reception opening and lying against the stop, wherein said device also comprises a pressing mechanism, which suitably acts in a direction substantially perpendi-cularly to the direction of insertion of the strip, on the rear side of the test strip, which pressing mechanism, when inserting a test strip, is in a resting position - remote from the test strip and, when the test strip is lying against the stop, is adapted to move into a pressing position in which it presses the test strip 10 against the window,.. the pressing force of said pressing . mechanism being substantially uniform in the positions - corresponding to various thicknesses of the test strips.
` In another aspect of the inventio~ there is provided a method of optically measuring a test zone of a test strip comprising: introducing the test strip along-side a window for optical viewing, providing a stop to limit movement of the test strip along side the window, to a position in which the tes-t zone is in opposed relation-ship with said window, urging said test zone against said window, such that said test zone.is positioned and firmly held against said window, and optically measuring said test zone through said window.
Suitably the.window may form part of a wall of the housing and it is appropriate that the window be fixed so as not to be moveable responsive to the pressing mechanism. On the other hand, the window could be adjust-ably moveable to different positions to allow for possible different locations of the test zone on different strips - ~ lS~4 since, of course, it is important that the test zone to be evaluated be opposite the window when the strip is held firmly for the evaluation of the test zone.
Since the pressing mechanism used according to the present invention is, upon inserting a test strip, in a resting position remote therefrom, the test strip can be very easily introduced into the reception open-ing until it comes to rest against the stop. By appropriate means, the pressing mechanism is moved -against the rear side of the test strip at the moment that this lies against the stop. For this purpose, there can be used, for example, a photocell device positioned in the region of the stop which cooperates with an electromagnetic operation of the pressing ! mechanism. Furthermore, according to the present invention, the pressing mechanism is constructed in such a manner that its pressing force is substantially e~ual in the positions corresponding to different thicknesses of the test strips. When using the above-mentioned electromagnetic means, the coil of the electromagnet operating the pressing mechanism can be so constructed, in known manner, that the strength of the magnetic field is substantially constant in the range of movement of the coiI core corresponding to the various possible test strip thicknesses so that a constant action of force also results. The operating ~ 1~8064 device by means of which the movement of the pressing mechanism from its resting position into its pressing position is initiated can be constructed in various ways, for example, in the form of a manually operated release button. However, an operating device is preferably provided in the region of the stop so that it is moved by an inserted test strip, for example, the above-méntioned light barrier comprising a source of light and a photocell in the region of the -stop for the test strip.
In comparison with the above-mentioned electro-magnetic embodiment of the device according to the present invention, a mechanical means is advantageous because it does no~. require a supplementary source of energy. Preferred embodiments of such mechanical means are described hereinafter.
.
A spring mechanism i9 preferably used in order to produce the force necessary for the pressing mechan-ism. It is in positive connection, via force trans-mitting means, with the pressing mechanism, the force transmission preferably being such that the transmission ratio of the force transmission and the force of the spring mechanism change substantlally reciprocally in the range of movement corresponding to various test strip thicknesses. The spring mechanism is preferably a mechanical spring, for example, a spiral or coil 0 ~ 4 i -8-spring~ However, a pneumatic piston-cylinder arrange-ment can, for example, also be used equally advantage-;~ ously. Such spring mechanisms normally have a force which is dependent upon their degree of tension.
This is, as mentioned above, unfavourable in the case of direct force transmission to the pressing mechanism `j because the positioning of the test strip in a direction at right-angles to the thickness of the test strip is thereby different if test-strips of differing thick-ness are employed. -The force transmission used accord- -ing to the present invention can, for example, be constructed in the form of a cam plate upon which the spring mechanism acts at a definite angle via a roller. In such a case, the angle between the direction of action of the spring mechanism and the ` effective surface of the cam plate determines the ; force transmission. It is, therefore, readily possible I to make the curve of the cam plate such that its orce transmission changes, according to the present invention, reciprocally to the change of the spring force.
According to a further preferred embodiment of the present invention, the range of movement of the pressing mechanism includes an apex: on the side of its range of movement proximal to the test strip, a force acts upon the pressing méchanism towards the test strip whereas on the side of the r~nge of movement remote from the test strip, referred to the apex, a , .
~ 1~806~
t _9_ force acts upon the pressing mechanism away f~om the test strip. Thus, the position of the apex is such that the pressing mechanlsm, in the position corres-` ponding to this apex, still does not lie against the thickest test strip to be measured. T~ith such a con-struction, an especially dependable and simple operat-ing of the pressing mechanism can be achieved because the range of movement of the pressing mechanis~ has a stable resting position.
In an especially preferred manner, the force transmission between the spring mechanism and the pressing mechanism is accom~lished with the help of a lever mechanism which can be tilted about a lever axis and has two articulated connections for the articulation of the spring mechanism. This lever mechanism can be advantageously constructed in such a manner that a substantially uniforln pressure of the pressing mechanism upon the test strip is achieved, inde-pendently of the thickness thereof. By means of the arrangement of the articulated connections and of the articulation point of the preferably used tension or pres-sure spring on the lever mechanism, in each case relative to the axis of the lever mechanism and to the guide of the pressing mechamism, the leverages are fixed which determine the force transmission between the spring and the pressing mechanism. As will be explained in more detail hereinafter, these leverages change when . ~ .
., ~
. _ the pressing mechanism assumes different positions in the case of the lying against of test strips of different thickness and, conse~uently, the correspond-ing rotation positions of the lever mechanism are also different. The positions of the pressing mechanism pressing against the test strip, which differ accord-ing to the thickness of the test strip, result, on ` the other hand, in automatically different deflections of the spring and thus in different spring forces.
According to the present invention, the spring ratings, on the one hand, and the dimensioning of the mentioned constructional parts, on the other hand, are such that the mentioned leverages and the force of the spring ~ change substantially reciprocally to one another when : the lever mechanism assumes different rotational position~ in the pressing position in the case of variou9 test strip thicknesse~. By means of this preferred construction, a pressing force is ac~ieved which is almost independent of the te~t strip thick-ness, a space-saving and economic method of construct-ion thereby being possible at the same time.
According to a preferred embodiment of the present invention, the tilting range of the lever mechanism i~cludes a position in which the axis of the fulcrum of the spring on the lever mechanism, the lever mechanism and the tilting axis of the spring on the side remote from the lever mechanism :, `
1~8~4 lie in one plane. In this position, the spring is stressed to a maximum, i.e. it is the apex of the tilting range. In the case of tilting the lever mechanism in both directions away from the apex, the spring is relieved, whereby, in practice, for press-ing the test strip, the lever mechanism is, by suit-able means, for example the test strip itself, or by an appropriate drive housed in the apparatus, moved from a position of the tilting range lying on one side of the apex, against the force of the spring, towards the apex. ~en the apex is passed, the spring is again relieved so that the lever mechanism, on the other side of the tilting range, receives a tilting moment away from the apex due to the spring. In the case o this embodiment, too, there is, in the apex position, also a clearance distance between the press-ing mechanism and the strip, even for very thick test strips. The result of this is that the tilting move-ment of the lever mechanism, after passing the~apex, continues further, driven by the spring, until the mentioned clearance distance has been covered by the pressing mechanism. By means of this constructional measure, a substantial uniformity of the pressing force on test strips of different thickness and, simultaneously, a precise positioning of the test strips in a longitudinal direction is again achieved.
According to a further preferred emkodiment, .
1:16~0~
the lever mechanism can be operated by the test strip itself. In practice, the test strip is inserted into the reception opening until it impinges against a corresponding stop surface of the lever mechanism.
Upon further insertion of the test strip into the reception opening, the lever mechanism is prefera~ly moved against the force of the spring towards the apex~ It is especially advantageous when the arrange--me~t of the test strip stop on the inner end of the reception opening and the leverages of the lever mechanism are so dimensioned that, when the test strip is lying against the stop, the lever mechanism is tilted outwardly over the apex of the tilting range.
~he result of this is that the tilting movement of the lever mechanism, driven by the ~orce of the spring, automatically runs further when the introduction of the test strip into the reception opening is finished and the test strip lies against the stop. The intro-duced test strip is, at this moment, because of the above-mentioned clearance, still free, whereas the lever mechanism undergoes a rapid snapping movement which ends when the pressing mechanism lies against the test strip. The main advantage of such a form of construction is that the test strip can be introduced especially easily into the apparatus, no special drive for the pressing mechanism of the test strip is necess-ary and the test strip is very precisely fixed, even in its longitudinal position.
l 1680~4 The lever mechanism is preferably constructed as a cam plate. The pressing mechanism can, in particular, be constructed as a double-jointed, suspended pressing plate or as a laterally guided ; piston.
A further advantageous embodiment of the present invention serves for the return of the pressing mechan-ism from the pressing position into the resting position. According to this embodiment, the housing can be moved longitudinally for the removal of the test strip. Upon moving the housing, the cam plate is, preferably via an additional cam, brought together with an appropriate positionàlly fixed constructional part of the measuring apparatus, for e~ample a ratchet present in the path of movement of the mentioned cam, in such a manner that, upon moving the housing counter to the direction of insertion of the test strip, thus ; usually upon pulling out the housing of the position-ing device from the measuring apparatus, the cam plate is tilted back from the pressing position into the resting position. The em~odiment permits an especially simple removal of the test strip from the measuring apparatus. An especial advantage is obtained in the case of a combination ~ith the mentioned operation of the cam plate by the test strip. Thus, in this case, the test strip is pushed a little outwardly by the cam plate over its stop surface into the reception ' . ' I
-8~B4 opening so that it can subsequently be removed especially easily. The same advantage is also achieved when the cam plate is constructed so as to be tiltable backwardly by means of an appropriate drive.
The present invention will now be described in more detail, with reference to the embodiments illustrated in the accompanying drawings, in which: -Fig.l is a schematic side view of a device according to the present invention, with the cover-removed;
Fig.2 is a geometrical representation of the principle for explaining thb prevailing leverages and measurements in various positions of the cam plate; and Figs.3a to 3c is a further embodiment of the present inventiorl, showing three different positions of the cam plate and of the pressing mechanism.
Fig.l of the accompanying drawings shows a device according to the present invention in which the pressing mechanism for the test strips is in the resting position. In a housing 20, there is arranged, near side 21 which faces the photoreceiver (not shown), a reception opening 2 for a test strip 1. The reception opening is of appro~imately rectangular cross-sectlon, the shape of which corresponds substantiàlly to the shape of the test strips to be inserted. The opening is outwardly bounded by a wall 22, while on the inner . . .
-0~4 - 15 ~
side thereof there is provided an insert 23 which simultaneously receives a pressure piston 9 in its end lying in the middle of the housing 20. The wall 22 is provided with a window 10 in the range of which a test zone 14 of the test strip 1 is to lie when the test strip 1 is fully inserted. For this positioning of the test strip 1, the inner end 13 of the reception opening 2 is provided with a stop 3 which extends on both sides of a cam plate 6, only the part lying behind the cam plate 6 being indicated by a broken line. In a usual embodiment of the device, the stop 3 is about 6 mm. from the middle of the test zone 14, at which distance the test zone 14 comes to lie directly below the window 10.
The cam plate 6 is rotatably fixed on to the housing by an axis 7. The cam plate 6 has a cam 8 which engages directly on the piston 9. Furthermore, via an articulated joint 24, a pressure spring 5 is fixed on to the cam plate 6. The other end of the pressure spring 5 is attached in an ar~ticulated manner on a tilting a~is 25 on the housing. The axis 7 of the cam plate 6 and the tilting axis 25 lie in the same plane.
The cam plate 6 is laterally, i.e. towards the test strip 1, provided with a contact surface 26 which, in the open position of the device, i.e. in the illus-trated resting position, projects up to the window 10.
During insertion of the test strip 1 into the open-ing 2, the end of the test strip comes to lie against the contact surface 26. Upon further insertion of the test strip 1 into the opening 2, the cam plate 6 is rotated clockwise about its axis 7. In the case of this rotational movement, the spring 5 is first tensioned until the axis 7, the articulated joint 24 and the tilting axis 25 lie on one line in the side view illustrated in the Figure. Regarded spatially, the three axes 7, 24 and 25, which run substantially parallel to one another, then lie in one plane. This position is the apex of the tilting movement of the cam plate. Instead of the illustrated pressure spring 5, there can, of course, also be used a tension spring which then, for example, in the ~ case of a construction which otherwise corresponds ; to tl~e illustrated embodiment, would have to have ; its tilting axis 25 to the left of the articulated joint 24 in Fig. 1.
During the above-described first part of the rotating movement of the cam plate 6, the cam ~ has passed through a clearance possibly present between it and the under side of the pressing piston 9 and now lies on the lower side of the piston 9~ The piston 9 has also already been pressed upwardly somewhat but has not yet passed into the region of the reception open-ing 2. When the cam plate 6 is at the apex, the contact 0 ~ 4 surface 26 still projects a little to the left in the Figure with regard to the stop 3. Upon further insertion of the test strip 1, this comes to lie against the stop 3, which determines its longitudinal position.
At this mo~ent, the cam plate 6 has passed the apex and, driven by the force of the spring 5, undergoes a snapping movement in which the test strip 1 is firmly gripped. The height of the piston 9 and the leverages of the cam plate 6 are such that the piston 9, even in the case of a very bhick test strip 1, does not immediately lie against the rear side 15 of the test strip 1. On the contrary, the cam plate ~, before coming to lie against the test strip 1, is to be tilted to such an extent that the force of the spring 5 transmitted to the piston 9 by the lever transmission, which is des cribed hereinafter in more detail, suffices reliably to hold the test strip 1 firmly.
The housing 20 o~ the device according to the present invention is preferably mounted in a sliding mounting (not shown in Fig. 1) so as to be movable in the longitudinal direction indicated by the double arrow 18. For measuring, the housing 20 is moved to the right in Fig. 1, a cam 11 of the cam plate 6 thereby slipping over a ratchet 17 which is tiltable about an axis 16 and is thereby tilted clockwise. Thereafter, the ratchet 17 drops back into the position illust-rated in Fig. 1 and is secured against rotation in a 1 1680~4 counterclockwise direction. For the ejection of a test strip 1, the whole housing 20 is moved towards the left in Fig. 1 until the cam 11 of the cam plate 6 engages with the right edge of the ratchet 17. Upon further movement of the housing 20 to the left, the cam plate 6 is thereby tilted back counterclockwise, the pressing piston 9 thereby being released from the rear side 15 of the test strip 1 and the test strip 1 is pushed to the left by the contact surface 26 outwardly of the reception opening 2. Thereafter, the test strip 1 can be removed particularly easily from the measurement device.
Upon tilting the cam plate 6, the cam 11 also operates a switch 12 for switching the optical measuring device on and off.
Fig. 2 shows, in geometric schematic represent-ation, the lever acting upon the cam plate 6 in two different cam plate positions, the first position being illustrated by an unbroken line and the second position by a broken line. In the first position, the cam plate 6 has, in its snapping movement into the pressing position, just passed the apex and the second position corresponds to the pressing position in the case of a comparatively thin test strip.
Fig. 2 is intended to clarify the principle of the operating leverages and is not to be regarded as being limiting in any way.
8~4 Generally speaking, the cam plate Ç repr~sents a lever mechanism with two levers A and B, a lever axis 7' being between the two levers. The fulcrum 8' is associated with the operating cam 8, this fulcrum 8' transmitting the movement, via transmission rod 30 and coupling 31, to a piston 9' which, in this case, is constructed as a pressure plate and guided in a -~ertical direction. The line T-T marks the position of the lower side of the thickest test strip to be measured, in the state of being pressed against the window of the optical system.
Spring S' is attached to the articulated joint 24', the other end of the spring S' being tiltably - mounted on tilting axis 25'.
For the calculation of the force acting on the ` pressure plate 9', the effective lever lengths of the levers A and B must be used, these being the projections of these levers at right-angles to the acting forces.
In the drawing, these lever lengths are indicated by the following references:
bl: efective force lever B in the first position b2: effective force lever B in the second position al: effective force lever A in the first position a2: effective force lever A in the second position The force F emanating from the spring is the product of the spring path s and the spring rating c.
; The spring is prestressed and the spring path s is .. . .
~ 1680~
calculated as the difference of the length of the spring in the unstressed state Lo and the spring length in the particular position 1.
As can be seen from Fig. 2, the lever lengths a and b and the spring lengths 1 are different depending upon the position of the cam plate 6 or of the here schematically illustrated lever mechanism.
After passing the apex, the lever length b increases in a clockwise direction, whereas the lever length a decreases.~ In this way, the leverage of the spring force on the pressing plate 9' becomes ever greater.
At the sarne time, the force of the spring 5' decreases because of its increasing elongation. The dimensions of the device according to the present invention can now be made such that these two counter effects are almost compensated by each other and thus, over a certain tilting range, the force acting on the pressing plate and thus on the test strip 1 remains almost constant.
For a spring with an untensioned length Lo of 18.3 mm.
and a spring rating of 0.01 Newton (N)/mm., the following Table shows, by way of example, this advantageous result:
~ ~806~
TA~LE
test strip spring spring spring a b pressure on thickness length path s force mm mm. the test in mm. 1 in mm. = Lo-} F = . strip in mm. c x s N P = a N
, .
0 ~ 3 12 ~ 44 5 ~ 86 0~ 586 5 ~ 1 11.8 1 ~ 3553 0~4 12022 6~08 0~608 5~2 11~6 1~3563 0~ 5 11 ~ g8 6~ 32 0~ 632 5~ 25 11.5 lo 3843 0~6 11~78 6~52 0~652 5~3 11~3 1~3901 100~ 7 11.58 6~ 72 0~ 572 5 ~ 35 11 1.3816 0~3 11~3- 7~00 0~700 5~4 10~7 1~387 0 ~ 9 11 ~ 1 702 0~ 720 5 ~ 45 10.4 1.3739 1~0 10~9 7~ 0~740 5~5 10~2 1~3723 ~1 10~75 7 55 0~755 5~55 9~9 1~3467 As can be seen from the above Table, in the case of a test strip thickness of 0. 3 mm~ I the spring force is 0~ 586 ~ and, in the case of a test strip thickness of 1.1 mmO, is 0~755 N. Thus, in the case of a very thick test strip, the spring force is almost 30%
greater than in the case of a very thin test strip.
On the other hand, because of the reciprocal change of the leverages, the pressure on the test strips changes to a far lesser extent. In the case of the embodiment illustrated in the Table, in the case of average test strip thicknesses, it achieves a maximum _ ... . . . ~
8~6~
value which, however, only differs by less than 4%
from the smallest value. ~ereas the first-mentioned force difference, as experience demonstrates, leads to a considerable ine~cactitudë of the measurement result in the case of optical evaluation of the test strip, the measurement result is only very slightly falsified by the remaining small pressure differences in the case of the apparatus according to the present invention.
The preferred èm~odiment of the present invention illustrated in Figs.3a to 3c of the accompanying drawings differs from the embodiment illustrated in Fig.l of the accompanying drawings especially in that the pressing device is constructed as a double-jointed suspended pressing plate 9" instead of as a laterally guided piston 9. Other~ise, the same reference numerals indicate the corresponding parts of the embodiment of Fig.l. Constructional parts which are changed in comparison with the embodiment of Fig.l or which are arranged in a different manner are addition-ally indicated by a double prime. These are, in particular, the cam plate 6", the a~is 7", the press-ing plate 9", the additional cam 11", a sprin~
mechanism constructed in this case as a tension spring 5" with a cam disc side-articulated joint 24"
and a tilting mount 25" and a cam 8" which acts as an articulated joint between the cam plate 5" and the pressing plate 9".
.
' "`` 1~8V~
~ ~ j As can be seen from Figs. 3a to 3c, the press-ing plate 9'` is double-jointedly suspended by two joints 30 and 31 so that it lies against the rear side 15 of the test strip 1 and, consequently, a precisely vertical action of force of the pressing plate 9" on the test strip 1 is guaranteed which, in turn, lies ayainst the window 10. For holding the press-ing plate 9" in the resting position, two mountings 32 and 33 are provided which are attached to the housing 20 in an appropriate manner.
Fig. 3a shows the resting position of the pressing device 9", the test strip 1 just having been inserted into the reception opening of the apparatus to such an extent that it lies against the contact surface 26 of the cam plate 6". In Fig. 3b, the cam plate 6" is present just at the apex of its tilting movement, the spring 5" being tensioned to a maximum, the axis of the articulated joint 2~", the lever axis 7'` and the axis of the tilting mount 25", lying on one plane. At this moment, the test strip 1 is in a position shortly before the stop 3, which is substantially obscured in Fig. 3b.
When the test strip is further moved in the insertion direction, then it finally impinges against the stop 3 in the manner illustrated in Fig. 3_. Due to the force of the spring 5", the cam plate 6" is moved into the pressing position, iilustrated in Fig. 3c, in which the test strip 1 is dependably and exactly positioned.
:
. . ,
Moxe particularly the device comprises a housing with a reception opening, on the inner end of which there is a stop for the test strip, and a window which is positioned opposite the test zone of a test strip inserted into the reception opening and lying against the stop.
The precise positioning of a medical test strip in an appropriate evaluation device, usually a remission photometer, is of decisive importance for the exactitude of the evaluation of the test strip. On the one hand, it is, of course, important that the test strip lies, in the longitudinal direction, correctly below the window of the optical measuring device in order that only the appropriate test zone lies in the measurement area and not perhaps a part of the carrier material, which would falsify the measurement result. On the other hand, it is extremely important that the distance between the optical measuring device and the surface of the test zone can be reproduced very precisely because, depending upon the construction of the optical system, the measured intensity enters into the result with the second to fourth power of the distance between the measurement field and the photoreceiver. In the case of a typical distance of 8 mm., a variation of the distance of only 0.1 mm. gives an error which is from 2.5 to 5%. Especial difficulties arise from the fact that, if possible, test strips of different manufacture and for ..~g different medical parameters are to be measured with one apparatus. The thickness of these test strips can differ considerably in the region of the test zone.
In the case of known apparatus, the test strips are introduced into a device provided therefor and firmly held in the measurement position by means of a leaf spring. In these devices, positioning is un-satisfactory not only in the longitudinal direction of the test strip but also with regard to the distance from the optical measuxement system. It can happen relatively easily that when the test strip is inserted, it does not lie completely against the stop because the leaf spring has already exerted a considerable resist-ance to the insertion. On the other hand, it can also quite easily happen that the test strip, after insertion, is again pulled out of the apparatus to a small extent, especially when the hands of the person operating the device are moist, which can frequently occur in the laboratory, and consequently stick somewhat to the test strip.
Furthermore, as has been recognized by the present invention, positioning at right-angles to the surface of the test strip can also be insufficiently exact when test strips of varying thickness are to be measur~d. Thus, the tension of the leaf spring is to a considerable extent, dependent upon the thickness of the test strip. The distance between the test zone and the optical measurement system also changes correspondingly to an extent which is unacceptable when a high degree of .
1 1~8~4 exactitude of the measurement is required.
Oftentimes the window in the reception opening has to be an open frame (e.g. to allow air to be in contact with the test piece) and in these cases the unsatisfactory results with known devices can easily be explained by the fact that different test zones are pressed into this frame to a different extent.
However, in the present invention it has been found, that even in apparatus with a firmly positioned closed window, for~ example of glass, the measuring results depend in most cases heavily on the strength of the force by which the test zone is pressed against the window.
Therefore, it is an object of the present invention so to improve the position of the test strips for optical-medical measurements that a very accurate measurement result is achieved.
.
.'5 680~
In one aspect of the invention there is provided a device for positioning and firmly holding a test strip for optical-medical measurements' the device includes a housing which has a passage for receiving a test strip having a test zone for optical examination, a stop in the housing limits insertion of the strip in the passage; a window is provided which is adapted to be in opposed ; relationship with the test zonej when the inner end of the strip is against the stop' a pressing means is moveable from a rest position remote from the strip to a holding `~ position in which the test zone is urged against the window, when the inner end of the strip is against the stop. In this way the test zone of the strip is positioned and firmly held against the window~
In a particularly advantageous embodiment the pressing means transmits a substantially uniform pressing force to the strip, independently of the thickness of the strip.
Thus, in particular the invention provides a device for positioning and firmly holding a test strip for optical-medical measurements, said device comprising a housing with a reception opening, on the inner end of which there : is a stop for the test strip, and a window which is positloned opposite the test zone of a test strip inserted 0 ~ 4 into the reception opening and lying against the stop, wherein said device also comprises a pressing mechanism, which suitably acts in a direction substantially perpendi-cularly to the direction of insertion of the strip, on the rear side of the test strip, which pressing mechanism, when inserting a test strip, is in a resting position - remote from the test strip and, when the test strip is lying against the stop, is adapted to move into a pressing position in which it presses the test strip 10 against the window,.. the pressing force of said pressing . mechanism being substantially uniform in the positions - corresponding to various thicknesses of the test strips.
` In another aspect of the inventio~ there is provided a method of optically measuring a test zone of a test strip comprising: introducing the test strip along-side a window for optical viewing, providing a stop to limit movement of the test strip along side the window, to a position in which the tes-t zone is in opposed relation-ship with said window, urging said test zone against said window, such that said test zone.is positioned and firmly held against said window, and optically measuring said test zone through said window.
Suitably the.window may form part of a wall of the housing and it is appropriate that the window be fixed so as not to be moveable responsive to the pressing mechanism. On the other hand, the window could be adjust-ably moveable to different positions to allow for possible different locations of the test zone on different strips - ~ lS~4 since, of course, it is important that the test zone to be evaluated be opposite the window when the strip is held firmly for the evaluation of the test zone.
Since the pressing mechanism used according to the present invention is, upon inserting a test strip, in a resting position remote therefrom, the test strip can be very easily introduced into the reception open-ing until it comes to rest against the stop. By appropriate means, the pressing mechanism is moved -against the rear side of the test strip at the moment that this lies against the stop. For this purpose, there can be used, for example, a photocell device positioned in the region of the stop which cooperates with an electromagnetic operation of the pressing ! mechanism. Furthermore, according to the present invention, the pressing mechanism is constructed in such a manner that its pressing force is substantially e~ual in the positions corresponding to different thicknesses of the test strips. When using the above-mentioned electromagnetic means, the coil of the electromagnet operating the pressing mechanism can be so constructed, in known manner, that the strength of the magnetic field is substantially constant in the range of movement of the coiI core corresponding to the various possible test strip thicknesses so that a constant action of force also results. The operating ~ 1~8064 device by means of which the movement of the pressing mechanism from its resting position into its pressing position is initiated can be constructed in various ways, for example, in the form of a manually operated release button. However, an operating device is preferably provided in the region of the stop so that it is moved by an inserted test strip, for example, the above-méntioned light barrier comprising a source of light and a photocell in the region of the -stop for the test strip.
In comparison with the above-mentioned electro-magnetic embodiment of the device according to the present invention, a mechanical means is advantageous because it does no~. require a supplementary source of energy. Preferred embodiments of such mechanical means are described hereinafter.
.
A spring mechanism i9 preferably used in order to produce the force necessary for the pressing mechan-ism. It is in positive connection, via force trans-mitting means, with the pressing mechanism, the force transmission preferably being such that the transmission ratio of the force transmission and the force of the spring mechanism change substantlally reciprocally in the range of movement corresponding to various test strip thicknesses. The spring mechanism is preferably a mechanical spring, for example, a spiral or coil 0 ~ 4 i -8-spring~ However, a pneumatic piston-cylinder arrange-ment can, for example, also be used equally advantage-;~ ously. Such spring mechanisms normally have a force which is dependent upon their degree of tension.
This is, as mentioned above, unfavourable in the case of direct force transmission to the pressing mechanism `j because the positioning of the test strip in a direction at right-angles to the thickness of the test strip is thereby different if test-strips of differing thick-ness are employed. -The force transmission used accord- -ing to the present invention can, for example, be constructed in the form of a cam plate upon which the spring mechanism acts at a definite angle via a roller. In such a case, the angle between the direction of action of the spring mechanism and the ` effective surface of the cam plate determines the ; force transmission. It is, therefore, readily possible I to make the curve of the cam plate such that its orce transmission changes, according to the present invention, reciprocally to the change of the spring force.
According to a further preferred embodiment of the present invention, the range of movement of the pressing mechanism includes an apex: on the side of its range of movement proximal to the test strip, a force acts upon the pressing méchanism towards the test strip whereas on the side of the r~nge of movement remote from the test strip, referred to the apex, a , .
~ 1~806~
t _9_ force acts upon the pressing mechanism away f~om the test strip. Thus, the position of the apex is such that the pressing mechanlsm, in the position corres-` ponding to this apex, still does not lie against the thickest test strip to be measured. T~ith such a con-struction, an especially dependable and simple operat-ing of the pressing mechanism can be achieved because the range of movement of the pressing mechanis~ has a stable resting position.
In an especially preferred manner, the force transmission between the spring mechanism and the pressing mechanism is accom~lished with the help of a lever mechanism which can be tilted about a lever axis and has two articulated connections for the articulation of the spring mechanism. This lever mechanism can be advantageously constructed in such a manner that a substantially uniforln pressure of the pressing mechanism upon the test strip is achieved, inde-pendently of the thickness thereof. By means of the arrangement of the articulated connections and of the articulation point of the preferably used tension or pres-sure spring on the lever mechanism, in each case relative to the axis of the lever mechanism and to the guide of the pressing mechamism, the leverages are fixed which determine the force transmission between the spring and the pressing mechanism. As will be explained in more detail hereinafter, these leverages change when . ~ .
., ~
. _ the pressing mechanism assumes different positions in the case of the lying against of test strips of different thickness and, conse~uently, the correspond-ing rotation positions of the lever mechanism are also different. The positions of the pressing mechanism pressing against the test strip, which differ accord-ing to the thickness of the test strip, result, on ` the other hand, in automatically different deflections of the spring and thus in different spring forces.
According to the present invention, the spring ratings, on the one hand, and the dimensioning of the mentioned constructional parts, on the other hand, are such that the mentioned leverages and the force of the spring ~ change substantially reciprocally to one another when : the lever mechanism assumes different rotational position~ in the pressing position in the case of variou9 test strip thicknesse~. By means of this preferred construction, a pressing force is ac~ieved which is almost independent of the te~t strip thick-ness, a space-saving and economic method of construct-ion thereby being possible at the same time.
According to a preferred embodiment of the present invention, the tilting range of the lever mechanism i~cludes a position in which the axis of the fulcrum of the spring on the lever mechanism, the lever mechanism and the tilting axis of the spring on the side remote from the lever mechanism :, `
1~8~4 lie in one plane. In this position, the spring is stressed to a maximum, i.e. it is the apex of the tilting range. In the case of tilting the lever mechanism in both directions away from the apex, the spring is relieved, whereby, in practice, for press-ing the test strip, the lever mechanism is, by suit-able means, for example the test strip itself, or by an appropriate drive housed in the apparatus, moved from a position of the tilting range lying on one side of the apex, against the force of the spring, towards the apex. ~en the apex is passed, the spring is again relieved so that the lever mechanism, on the other side of the tilting range, receives a tilting moment away from the apex due to the spring. In the case o this embodiment, too, there is, in the apex position, also a clearance distance between the press-ing mechanism and the strip, even for very thick test strips. The result of this is that the tilting move-ment of the lever mechanism, after passing the~apex, continues further, driven by the spring, until the mentioned clearance distance has been covered by the pressing mechanism. By means of this constructional measure, a substantial uniformity of the pressing force on test strips of different thickness and, simultaneously, a precise positioning of the test strips in a longitudinal direction is again achieved.
According to a further preferred emkodiment, .
1:16~0~
the lever mechanism can be operated by the test strip itself. In practice, the test strip is inserted into the reception opening until it impinges against a corresponding stop surface of the lever mechanism.
Upon further insertion of the test strip into the reception opening, the lever mechanism is prefera~ly moved against the force of the spring towards the apex~ It is especially advantageous when the arrange--me~t of the test strip stop on the inner end of the reception opening and the leverages of the lever mechanism are so dimensioned that, when the test strip is lying against the stop, the lever mechanism is tilted outwardly over the apex of the tilting range.
~he result of this is that the tilting movement of the lever mechanism, driven by the ~orce of the spring, automatically runs further when the introduction of the test strip into the reception opening is finished and the test strip lies against the stop. The intro-duced test strip is, at this moment, because of the above-mentioned clearance, still free, whereas the lever mechanism undergoes a rapid snapping movement which ends when the pressing mechanism lies against the test strip. The main advantage of such a form of construction is that the test strip can be introduced especially easily into the apparatus, no special drive for the pressing mechanism of the test strip is necess-ary and the test strip is very precisely fixed, even in its longitudinal position.
l 1680~4 The lever mechanism is preferably constructed as a cam plate. The pressing mechanism can, in particular, be constructed as a double-jointed, suspended pressing plate or as a laterally guided ; piston.
A further advantageous embodiment of the present invention serves for the return of the pressing mechan-ism from the pressing position into the resting position. According to this embodiment, the housing can be moved longitudinally for the removal of the test strip. Upon moving the housing, the cam plate is, preferably via an additional cam, brought together with an appropriate positionàlly fixed constructional part of the measuring apparatus, for e~ample a ratchet present in the path of movement of the mentioned cam, in such a manner that, upon moving the housing counter to the direction of insertion of the test strip, thus ; usually upon pulling out the housing of the position-ing device from the measuring apparatus, the cam plate is tilted back from the pressing position into the resting position. The em~odiment permits an especially simple removal of the test strip from the measuring apparatus. An especial advantage is obtained in the case of a combination ~ith the mentioned operation of the cam plate by the test strip. Thus, in this case, the test strip is pushed a little outwardly by the cam plate over its stop surface into the reception ' . ' I
-8~B4 opening so that it can subsequently be removed especially easily. The same advantage is also achieved when the cam plate is constructed so as to be tiltable backwardly by means of an appropriate drive.
The present invention will now be described in more detail, with reference to the embodiments illustrated in the accompanying drawings, in which: -Fig.l is a schematic side view of a device according to the present invention, with the cover-removed;
Fig.2 is a geometrical representation of the principle for explaining thb prevailing leverages and measurements in various positions of the cam plate; and Figs.3a to 3c is a further embodiment of the present inventiorl, showing three different positions of the cam plate and of the pressing mechanism.
Fig.l of the accompanying drawings shows a device according to the present invention in which the pressing mechanism for the test strips is in the resting position. In a housing 20, there is arranged, near side 21 which faces the photoreceiver (not shown), a reception opening 2 for a test strip 1. The reception opening is of appro~imately rectangular cross-sectlon, the shape of which corresponds substantiàlly to the shape of the test strips to be inserted. The opening is outwardly bounded by a wall 22, while on the inner . . .
-0~4 - 15 ~
side thereof there is provided an insert 23 which simultaneously receives a pressure piston 9 in its end lying in the middle of the housing 20. The wall 22 is provided with a window 10 in the range of which a test zone 14 of the test strip 1 is to lie when the test strip 1 is fully inserted. For this positioning of the test strip 1, the inner end 13 of the reception opening 2 is provided with a stop 3 which extends on both sides of a cam plate 6, only the part lying behind the cam plate 6 being indicated by a broken line. In a usual embodiment of the device, the stop 3 is about 6 mm. from the middle of the test zone 14, at which distance the test zone 14 comes to lie directly below the window 10.
The cam plate 6 is rotatably fixed on to the housing by an axis 7. The cam plate 6 has a cam 8 which engages directly on the piston 9. Furthermore, via an articulated joint 24, a pressure spring 5 is fixed on to the cam plate 6. The other end of the pressure spring 5 is attached in an ar~ticulated manner on a tilting a~is 25 on the housing. The axis 7 of the cam plate 6 and the tilting axis 25 lie in the same plane.
The cam plate 6 is laterally, i.e. towards the test strip 1, provided with a contact surface 26 which, in the open position of the device, i.e. in the illus-trated resting position, projects up to the window 10.
During insertion of the test strip 1 into the open-ing 2, the end of the test strip comes to lie against the contact surface 26. Upon further insertion of the test strip 1 into the opening 2, the cam plate 6 is rotated clockwise about its axis 7. In the case of this rotational movement, the spring 5 is first tensioned until the axis 7, the articulated joint 24 and the tilting axis 25 lie on one line in the side view illustrated in the Figure. Regarded spatially, the three axes 7, 24 and 25, which run substantially parallel to one another, then lie in one plane. This position is the apex of the tilting movement of the cam plate. Instead of the illustrated pressure spring 5, there can, of course, also be used a tension spring which then, for example, in the ~ case of a construction which otherwise corresponds ; to tl~e illustrated embodiment, would have to have ; its tilting axis 25 to the left of the articulated joint 24 in Fig. 1.
During the above-described first part of the rotating movement of the cam plate 6, the cam ~ has passed through a clearance possibly present between it and the under side of the pressing piston 9 and now lies on the lower side of the piston 9~ The piston 9 has also already been pressed upwardly somewhat but has not yet passed into the region of the reception open-ing 2. When the cam plate 6 is at the apex, the contact 0 ~ 4 surface 26 still projects a little to the left in the Figure with regard to the stop 3. Upon further insertion of the test strip 1, this comes to lie against the stop 3, which determines its longitudinal position.
At this mo~ent, the cam plate 6 has passed the apex and, driven by the force of the spring 5, undergoes a snapping movement in which the test strip 1 is firmly gripped. The height of the piston 9 and the leverages of the cam plate 6 are such that the piston 9, even in the case of a very bhick test strip 1, does not immediately lie against the rear side 15 of the test strip 1. On the contrary, the cam plate ~, before coming to lie against the test strip 1, is to be tilted to such an extent that the force of the spring 5 transmitted to the piston 9 by the lever transmission, which is des cribed hereinafter in more detail, suffices reliably to hold the test strip 1 firmly.
The housing 20 o~ the device according to the present invention is preferably mounted in a sliding mounting (not shown in Fig. 1) so as to be movable in the longitudinal direction indicated by the double arrow 18. For measuring, the housing 20 is moved to the right in Fig. 1, a cam 11 of the cam plate 6 thereby slipping over a ratchet 17 which is tiltable about an axis 16 and is thereby tilted clockwise. Thereafter, the ratchet 17 drops back into the position illust-rated in Fig. 1 and is secured against rotation in a 1 1680~4 counterclockwise direction. For the ejection of a test strip 1, the whole housing 20 is moved towards the left in Fig. 1 until the cam 11 of the cam plate 6 engages with the right edge of the ratchet 17. Upon further movement of the housing 20 to the left, the cam plate 6 is thereby tilted back counterclockwise, the pressing piston 9 thereby being released from the rear side 15 of the test strip 1 and the test strip 1 is pushed to the left by the contact surface 26 outwardly of the reception opening 2. Thereafter, the test strip 1 can be removed particularly easily from the measurement device.
Upon tilting the cam plate 6, the cam 11 also operates a switch 12 for switching the optical measuring device on and off.
Fig. 2 shows, in geometric schematic represent-ation, the lever acting upon the cam plate 6 in two different cam plate positions, the first position being illustrated by an unbroken line and the second position by a broken line. In the first position, the cam plate 6 has, in its snapping movement into the pressing position, just passed the apex and the second position corresponds to the pressing position in the case of a comparatively thin test strip.
Fig. 2 is intended to clarify the principle of the operating leverages and is not to be regarded as being limiting in any way.
8~4 Generally speaking, the cam plate Ç repr~sents a lever mechanism with two levers A and B, a lever axis 7' being between the two levers. The fulcrum 8' is associated with the operating cam 8, this fulcrum 8' transmitting the movement, via transmission rod 30 and coupling 31, to a piston 9' which, in this case, is constructed as a pressure plate and guided in a -~ertical direction. The line T-T marks the position of the lower side of the thickest test strip to be measured, in the state of being pressed against the window of the optical system.
Spring S' is attached to the articulated joint 24', the other end of the spring S' being tiltably - mounted on tilting axis 25'.
For the calculation of the force acting on the ` pressure plate 9', the effective lever lengths of the levers A and B must be used, these being the projections of these levers at right-angles to the acting forces.
In the drawing, these lever lengths are indicated by the following references:
bl: efective force lever B in the first position b2: effective force lever B in the second position al: effective force lever A in the first position a2: effective force lever A in the second position The force F emanating from the spring is the product of the spring path s and the spring rating c.
; The spring is prestressed and the spring path s is .. . .
~ 1680~
calculated as the difference of the length of the spring in the unstressed state Lo and the spring length in the particular position 1.
As can be seen from Fig. 2, the lever lengths a and b and the spring lengths 1 are different depending upon the position of the cam plate 6 or of the here schematically illustrated lever mechanism.
After passing the apex, the lever length b increases in a clockwise direction, whereas the lever length a decreases.~ In this way, the leverage of the spring force on the pressing plate 9' becomes ever greater.
At the sarne time, the force of the spring 5' decreases because of its increasing elongation. The dimensions of the device according to the present invention can now be made such that these two counter effects are almost compensated by each other and thus, over a certain tilting range, the force acting on the pressing plate and thus on the test strip 1 remains almost constant.
For a spring with an untensioned length Lo of 18.3 mm.
and a spring rating of 0.01 Newton (N)/mm., the following Table shows, by way of example, this advantageous result:
~ ~806~
TA~LE
test strip spring spring spring a b pressure on thickness length path s force mm mm. the test in mm. 1 in mm. = Lo-} F = . strip in mm. c x s N P = a N
, .
0 ~ 3 12 ~ 44 5 ~ 86 0~ 586 5 ~ 1 11.8 1 ~ 3553 0~4 12022 6~08 0~608 5~2 11~6 1~3563 0~ 5 11 ~ g8 6~ 32 0~ 632 5~ 25 11.5 lo 3843 0~6 11~78 6~52 0~652 5~3 11~3 1~3901 100~ 7 11.58 6~ 72 0~ 572 5 ~ 35 11 1.3816 0~3 11~3- 7~00 0~700 5~4 10~7 1~387 0 ~ 9 11 ~ 1 702 0~ 720 5 ~ 45 10.4 1.3739 1~0 10~9 7~ 0~740 5~5 10~2 1~3723 ~1 10~75 7 55 0~755 5~55 9~9 1~3467 As can be seen from the above Table, in the case of a test strip thickness of 0. 3 mm~ I the spring force is 0~ 586 ~ and, in the case of a test strip thickness of 1.1 mmO, is 0~755 N. Thus, in the case of a very thick test strip, the spring force is almost 30%
greater than in the case of a very thin test strip.
On the other hand, because of the reciprocal change of the leverages, the pressure on the test strips changes to a far lesser extent. In the case of the embodiment illustrated in the Table, in the case of average test strip thicknesses, it achieves a maximum _ ... . . . ~
8~6~
value which, however, only differs by less than 4%
from the smallest value. ~ereas the first-mentioned force difference, as experience demonstrates, leads to a considerable ine~cactitudë of the measurement result in the case of optical evaluation of the test strip, the measurement result is only very slightly falsified by the remaining small pressure differences in the case of the apparatus according to the present invention.
The preferred èm~odiment of the present invention illustrated in Figs.3a to 3c of the accompanying drawings differs from the embodiment illustrated in Fig.l of the accompanying drawings especially in that the pressing device is constructed as a double-jointed suspended pressing plate 9" instead of as a laterally guided piston 9. Other~ise, the same reference numerals indicate the corresponding parts of the embodiment of Fig.l. Constructional parts which are changed in comparison with the embodiment of Fig.l or which are arranged in a different manner are addition-ally indicated by a double prime. These are, in particular, the cam plate 6", the a~is 7", the press-ing plate 9", the additional cam 11", a sprin~
mechanism constructed in this case as a tension spring 5" with a cam disc side-articulated joint 24"
and a tilting mount 25" and a cam 8" which acts as an articulated joint between the cam plate 5" and the pressing plate 9".
.
' "`` 1~8V~
~ ~ j As can be seen from Figs. 3a to 3c, the press-ing plate 9'` is double-jointedly suspended by two joints 30 and 31 so that it lies against the rear side 15 of the test strip 1 and, consequently, a precisely vertical action of force of the pressing plate 9" on the test strip 1 is guaranteed which, in turn, lies ayainst the window 10. For holding the press-ing plate 9" in the resting position, two mountings 32 and 33 are provided which are attached to the housing 20 in an appropriate manner.
Fig. 3a shows the resting position of the pressing device 9", the test strip 1 just having been inserted into the reception opening of the apparatus to such an extent that it lies against the contact surface 26 of the cam plate 6". In Fig. 3b, the cam plate 6" is present just at the apex of its tilting movement, the spring 5" being tensioned to a maximum, the axis of the articulated joint 2~", the lever axis 7'` and the axis of the tilting mount 25", lying on one plane. At this moment, the test strip 1 is in a position shortly before the stop 3, which is substantially obscured in Fig. 3b.
When the test strip is further moved in the insertion direction, then it finally impinges against the stop 3 in the manner illustrated in Fig. 3_. Due to the force of the spring 5", the cam plate 6" is moved into the pressing position, iilustrated in Fig. 3c, in which the test strip 1 is dependably and exactly positioned.
:
. . ,
Claims (31)
1. A device for positioning and firmly holding a test strip for optical-medical measurements, comprising:
a housing with a reception opening defined therein, a stop for the test strip on an inner end of said reception opening, a window in said housing adapted to be in opposed relationship with a test zone of a test strip inserted into the reception opening and having its inner end against the stop, a pressing mechanism having a range of move-ment, adapted to act on a rear side of the test strip, said pressing mechanism being in a resting position remote from the test strip during insertion of the strip in said opening and being adapted to move into a pressing position in which it presses the test strip against the window when the inner end of the test strip is against the stop, the pressing force of said pressing mechanism being sub-stantially uniform in the positions corresponding to various thicknesses of the test strip.
a housing with a reception opening defined therein, a stop for the test strip on an inner end of said reception opening, a window in said housing adapted to be in opposed relationship with a test zone of a test strip inserted into the reception opening and having its inner end against the stop, a pressing mechanism having a range of move-ment, adapted to act on a rear side of the test strip, said pressing mechanism being in a resting position remote from the test strip during insertion of the strip in said opening and being adapted to move into a pressing position in which it presses the test strip against the window when the inner end of the test strip is against the stop, the pressing force of said pressing mechanism being sub-stantially uniform in the positions corresponding to various thicknesses of the test strip.
2. A device according to claim 1, wherein said pressing mechanism acts in a direction substantially perpendicular to the direction of insertion of the test strip.
3. A device according to claim 1 or 2, wherein the move-ment of the pressing mechanism from the resting position into the pressing position is initiated by an operating device arranged in the region of the stop
4. A device according to claim 1 wherein the pressing mechanism is in positive connection with a spring mechanism, the transmission relationship of the force transmission and the force of the spring mechanism changing substantially reciprocally in the movement range corresponding to various test strip thicknesses.
5. A device according to claim 1 or 2, wherein the range of movement of the pressing mechanism includes a first range, in which a force acts in the direction of the test strip, and a second range, in which a force acts away from the test strip. the pressing mechanism at the apex separating the two ranges, still being spaced apart from the thickest test strip to be positioned and held.
6. A device according to claim 4, wherein the force transmission between the spring mechanism and the press-ing mechanism includes a lever mechanism tiltable about a lever axis, said lever mechanism having a first articulated joint for the articulation of the pressing mechanism and a second articulated joint for the articulation of the spring mechanism.
7. A device according to claim 6, wherein the spring mechanism is constructed as a tension or pressure spring which is articulated from the end of the spring remote from the lever mechanism in a tilting mount, the spring being prestressed and the arrangement of the articulated joints on the lever mechanism, the spring prestressing and the spring constants being such that the leverage, on the one hand, and the spring force, on the other hand, change substantially reciprocally in the tilting range of the lever mechanism corresponding to the thickness of the different test strips to be measured.
8. A device according to claim 6, wherein the operational tilting range of the lever mechanism has an apex in which the axis of the second articulated joint, the lever axis and the axis of the tilting mount of the spring mechanism, which run substantially parallel to one another, lie in one plane and in which the spring mechanism is tensioned to a maximum.
9. A device according to claim 6, 7 or 8, wherein the lever mechanism has, as operating device, a contact surface for the test strip by means of which it is tiltable by the test strip, the lever mechanism being so dimensioned that, when a test strip has an inner end against the stop, the lever mechanism is tilted over the apex of the tilting range.
10. A device according to claim 6, wherein the pressing mechanism is constructed as a doubly articulated, suspended pressing plate and the lever mechanism as a cam plate, the articulated joint between the pressing plate and the cam plate being formed by a cam on the cam plate cooperating with the rear side of the pressing plate.
11. A device according to claim 6, wherein the pressing mechanism is constructed as a laterally guided piston and the lever mechanism as a cam plate, the piston being operable by a cam on the cam plate.
12. A device according to claim 10 or 11, including a switch for the provision of energy for the measuring device, said switch being operated by a cam on the cam plate.
13. A device according to claim 6, 7 or 8, wherein the housing is, for the removal of the test strip, movable laterally and the lever mechanism cooperates with positionally fixed operating means in such a manner that movement of the housing counter to the insertion direction of the test strip tilts the lever mechanism in such a manner that the test strip is freed.
14. A device for positioning and firmly holding a test strip for optical medical measurement, comprising:
a housing, a passage in said housing for receiving a test strip having a test zone for optical examination, a stop in said housing to limit insertion of said strip in said passage, a window adapted to be in opposed relationship with said test zone with the inner end of the strip against said stop, pressing means moveable from a rest position remote from the strip to a holding position in which it urges said test zone against said window when the inner end of the strip is positioned against said stop, such that said test zone is positioned and firmly held against said window.
a housing, a passage in said housing for receiving a test strip having a test zone for optical examination, a stop in said housing to limit insertion of said strip in said passage, a window adapted to be in opposed relationship with said test zone with the inner end of the strip against said stop, pressing means moveable from a rest position remote from the strip to a holding position in which it urges said test zone against said window when the inner end of the strip is positioned against said stop, such that said test zone is positioned and firmly held against said window.
15. A device according to claim 14, in which said pressing means is adapted to transmit a substantially uniform pressing force to the strip, independently of the thickness of the strip.
16. A device according to claim 15, wherein said passage is defined adjacent a wall of the housing and said window being disposed in a fixed position in said wall.
17. A device according to claim 14, 15 or 16, wherein said pressing means acts in a direction sub-stantially perpendicular to the direction of insertion of the test strip.
18. A device for positioning and firmly holding a medical test strip, said device comprising:
a housing having a strip reception opening, means forming a stop at the inner end of the opening for the inserted end of the test strip and a window positioned to be opposite a predetermined test zone of the test strip when inserted into the reception opening and abutting against the stop, means for pressing substantially at right-angles on the rear side of the test strip towards said window, the pressing means being movable between a rest position wherein it is spaced from the rear side of the inserted test strip and a pressing position in which it presses the test strip against the window; and means responsive to the insertion of a test strip for moving the pressing means from the rest to the pressing position and for applying a pressing force which is substantially uniform in the positions corresponding to various thick-nesses of insertable test strips.
a housing having a strip reception opening, means forming a stop at the inner end of the opening for the inserted end of the test strip and a window positioned to be opposite a predetermined test zone of the test strip when inserted into the reception opening and abutting against the stop, means for pressing substantially at right-angles on the rear side of the test strip towards said window, the pressing means being movable between a rest position wherein it is spaced from the rear side of the inserted test strip and a pressing position in which it presses the test strip against the window; and means responsive to the insertion of a test strip for moving the pressing means from the rest to the pressing position and for applying a pressing force which is substantially uniform in the positions corresponding to various thick-nesses of insertable test strips.
19. The device according to claim 18 wherein the moving means includes an actuating member disposed in the region of the stop to initiate movement of the pressing means into the pressing position.
20. The device according to claim 19 wherein the moving means comprises a spring mechanism in positive connection with the pressing means and wherein the trans-mission relationship of the force transmission and the force of the spring mechanism changes substantially reciprocally in the movement range corresponding to a given range of test strip thicknesses.
21. The device according to claim 20 wherein the driving movement of the moving means on the pressing means includes a first range in which the force acts in the direction of the test strip and a second range in which the force acts away from the test strip wherein the pressing means at the apex separating the two ranges is spaced apart from the preselected thickest test strip to be measured.
22. The device according to claim 20 wherein the force transmission between the spring mechanism and the pressing means includes a lever mechanism tiltable about a lever axis, said lever mechanism having a first articu-lated joint for the articulation of the pressing means and a second articulated joint for the atriculation of the spring mechanism.
23. The device according to claim 22 wherein the spring mechanism comprises a spring which is articulated from the end of the spring remote from the lever mechanism in a tilting mount, the spring being prestressed and the arrangement of the articulated joints on the lever mechanism, the spring prestressing and the spring constants being such that the leverage, on the one hand, and the spring force, on the other hand, change substantially reciprocally in the tilting range of the lever mechanism corresponding to the thickness of the different test strips to be measured.
24. The device according to claim 23 wherein the operational tilting range of the lever mechanism has an apex in which the axis of the second articulated joint, the lever axis and the axis of the tilting mount of the spring mechanism, which run substantially parallel to one another lie in one plane and in which the spring mechanism is tensioned to a maximum.
25. The device according to claim 22 wherein the lever mechanism includes the actuating member which comprises a contact surface for the test strip through which the lever mechanism is tiltable by the test strip and wherein the lever mechanism is dimensioned such that when a test strip is lying against the stop the lever mechanism is tilted over the apex of the tilting range.
26. The device according to claim 22 wherein the pressing means comprises a doubly articulated, suspended pressing plate and the lever mechanism comprises a cam plate and wherein the articulated joint between the pressing plate and the cam plate comprises a cam on the cam plate cooperating with the rear side of the pressing plate.
27. The device according to claim 22 wherein the pressing means comprises a laterally guided piston and the lever mechanism comprises a cam plate and wherein the piston is operable by a cam on the cam plate.
28. The device according to claim 26 or 27 wherein the device is used in a measuring apparatus and further comprising a switch for the provision of energy for the measuring device and a cam on the cam plate for actuating the switch.
29. The device according to claim 22 wherein the cam plate includes means responsive to the lateral movement of the housing from a measuring apparatus to effect movement of the pressing means from the pressing to the rest position so that the test strip is freed.
30. A method of optically measuring a test zone of a test strip comprising:
introducing the test strip alongside a window for optical viewing, providing a stop to limit movement of the test strip, alongside the window, to a position in which the test zone is in opposed relationship with said window, and urging said test zone against said window, with a substantially uniform pressing force independently of the thickness of the strip, such that said test zone is positioned and firmly held against said window, and optically measuring said test zone through said window, and wherein, said test strip activates an operating mechanism for a pressing mechanism as it approaches said stop, said pressing mechanism being maintained in a rest position remote from said strip during introduction of said strip and being activated by said operating mechanism when the inner end of said strip is against said stop such that further introduction is prevented.
introducing the test strip alongside a window for optical viewing, providing a stop to limit movement of the test strip, alongside the window, to a position in which the test zone is in opposed relationship with said window, and urging said test zone against said window, with a substantially uniform pressing force independently of the thickness of the strip, such that said test zone is positioned and firmly held against said window, and optically measuring said test zone through said window, and wherein, said test strip activates an operating mechanism for a pressing mechanism as it approaches said stop, said pressing mechanism being maintained in a rest position remote from said strip during introduction of said strip and being activated by said operating mechanism when the inner end of said strip is against said stop such that further introduction is prevented.
31. A method according to claim 30 wherein said operating mechanism comprises a contact surface which is engaged by said test strip during said introduction, and moved from a first position towards said stop to a second position in which said inner end of said strip is against said stop said operating mechanism activating said pressing mechanism when said contact surface is in said second position.
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DEP3011223.3 | 1980-03-22 | ||
| DE19803011223 DE3011223C2 (en) | 1980-03-22 | 1980-03-22 | Device for positioning and holding a test strip for optical medical measurements |
| DEP3016198.9 | 1980-04-26 | ||
| DE19803016198 DE3016198A1 (en) | 1980-04-26 | 1980-04-26 | Mechanism positioning medical test strip in re-emission photometer - uses rotating cam to press strip against window when abutting end stop |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1168064A true CA1168064A (en) | 1984-05-29 |
Family
ID=25784502
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000372953A Expired CA1168064A (en) | 1980-03-22 | 1981-03-13 | Device for positioning a test strip for optical- medical measurements |
Country Status (6)
| Country | Link |
|---|---|
| US (1) | US4372682A (en) |
| EP (1) | EP0037484B1 (en) |
| AU (1) | AU538936B2 (en) |
| CA (1) | CA1168064A (en) |
| DE (1) | DE3163944D1 (en) |
| ES (1) | ES8202638A1 (en) |
Families Citing this family (15)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3226372A1 (en) * | 1982-07-14 | 1984-01-19 | Compur-Electronic GmbH, 8000 München | METHOD AND DEVICE FOR MEASURING REMISSIONS |
| DE3321785A1 (en) * | 1983-06-16 | 1984-12-20 | Boehringer Mannheim Gmbh, 6800 Mannheim | DEVICE FOR POSITIONING AND HOLDING A TEST STRIP FOR OPTICAL-MEDICAL MEASUREMENTS |
| US4833088A (en) * | 1987-09-25 | 1989-05-23 | Miles Inc. | Reagent strip handling mechanism |
| DE8716270U1 (en) * | 1987-12-09 | 1988-02-18 | Lre Relais + Elektronik Gmbh, 8000 Muenchen, De | |
| DE3844103A1 (en) * | 1988-12-28 | 1990-07-05 | Boehringer Mannheim Gmbh | TEST CARRIER ANALYSIS SYSTEM |
| DE3921391A1 (en) * | 1989-06-29 | 1991-01-10 | Lre Relais & Elektronik Gmbh | DEVICE FOR REMISSION-PHOTOMETRIC ANALYSIS OF LIQUID SAMPLES |
| US6394952B1 (en) | 1998-02-03 | 2002-05-28 | Adeza Biomedical Corporation | Point of care diagnostic systems |
| US6267722B1 (en) | 1998-02-03 | 2001-07-31 | Adeza Biomedical Corporation | Point of care diagnostic systems |
| USD434153S (en) * | 1998-04-20 | 2000-11-21 | Adeza Biomedical Corporation | Point of care analyte detector system |
| USD432244S (en) * | 1998-04-20 | 2000-10-17 | Adeza Biomedical Corporation | Device for encasing an assay test strip |
| DE19952215C2 (en) | 1999-10-29 | 2001-10-31 | Roche Diagnostics Gmbh | Test element analysis system |
| DE10338446A1 (en) * | 2003-08-21 | 2005-03-31 | Roche Diagnostics Gmbh | Positioning device for a test element |
| DE102004022757B4 (en) * | 2004-05-07 | 2006-11-02 | Lre Technology Partner Gmbh | Streifenauswerfer |
| US20130143246A1 (en) | 2011-12-02 | 2013-06-06 | Lifescan Scotland Ltd. | Hand-held test meter with analytical test strip ejection mechanism |
| CN116735504A (en) * | 2021-03-25 | 2023-09-12 | 江苏硕世生物科技股份有限公司 | Detection result reading device |
Family Cites Families (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE7042398U (en) * | 1971-04-01 | Boehringer Mannheim Gmbh | Sterilizable test strip holder on a test strip meter | |
| DE7042397U (en) * | 1971-04-15 | Boehringer Mannheim Gmbh | Test strip holder on a test strip meter | |
| US3604815A (en) * | 1968-04-22 | 1971-09-14 | Miles Lab | Reflectance meter |
| US3738730A (en) * | 1971-07-06 | 1973-06-12 | Aerojet General Co | Microscope attachment |
| US4033698A (en) * | 1975-10-10 | 1977-07-05 | International Business Machines Corporation | Apparatus for textile color analysis |
| US4248498A (en) * | 1978-06-29 | 1981-02-03 | Georges Michael P | Automatic microscope slide |
-
1981
- 1981-03-13 CA CA000372953A patent/CA1168064A/en not_active Expired
- 1981-03-17 DE DE8181101961T patent/DE3163944D1/en not_active Expired
- 1981-03-17 EP EP81101961A patent/EP0037484B1/en not_active Expired
- 1981-03-17 AU AU68447/81A patent/AU538936B2/en not_active Ceased
- 1981-03-18 US US06/244,988 patent/US4372682A/en not_active Expired - Fee Related
- 1981-03-18 ES ES500486A patent/ES8202638A1/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| ES500486A0 (en) | 1982-02-16 |
| EP0037484B1 (en) | 1984-06-06 |
| US4372682A (en) | 1983-02-08 |
| DE3163944D1 (en) | 1984-07-12 |
| AU6844781A (en) | 1981-10-01 |
| EP0037484A1 (en) | 1981-10-14 |
| ES8202638A1 (en) | 1982-02-16 |
| AU538936B2 (en) | 1984-09-06 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |